Phenotypic enhancement of longevity by environmental urea in Drosophila melanogaster

The phenotypic enhancement of longevity through a variety of environmental treatments, including dietary manipulations, has been observed in various species of animals, both vertebrate and invertebrate. Elucidating the mechanisms underlying such effects has provided insights into the physiological processes contributing to the determination of lifespan. Here, we report the enhancement of longevity in adult Drosophila melanogaster maintained on food supplemented with urea, a metabolic waste product occurring naturally in Drosophila cultures, especially at high larval densities. The impact of urea on longevity is shown to be through a decrease in the age-independent parameter (A) of the Gompertz equation, rather than the age-dependent parameter (alpha), which reflects the "rate of aging." We also present evidence suggesting that the urea-induced increase in longevity is mediated exclusively through a reduction in some aspect(s) of reproduction in adult flies maintained on urea-supplemented food.